..Although Chinese infants took longer to begin smiling, responding was similar in both cultures, despite differences in mothers' behavior: Chinese mothers played with the infants' arms; Canadian mothers played with the legs...

..These findings suggest a change in processing of complex sounds at around 33 weeks GA, with responding limited to the acoustic properties of the signal in younger fetuses but attention playing a role in older fetuses...

Maturation of human fetal responses to airborne sound in low- and high-risk fetuses